Contour abrading machine and method



Feb. 23, 1965 R. c. BURNHAM 3,170,272

CONTOUR ABRADING MACHINE AND METHOD Filed June 5, 1963 3 Sheets-Sheet 1 vaca am source INVENTOR. I Ric/lard CEurn/vam BY av -4774a,!

Feb. 23, 1965 R. c. BURNHAM 3,170,272

CONTOUR ABRADING MACHINE AND METHOD Filed June 5, 1965 3 Sheets-Sheet 2 INVENTOR. R/c/mrcl C. Burn/mm BY 61 427 A! tutomf7s 23, 9 R. c. BURNHAM R 3,170,272

CONTOUR ABRADING MACHINE AND METHOD Filed June 5, 1963 5 Sheets-Sheet :5

INVENTOR. Ric/m rd C. Burn/mm aux-m n7 5 United States Patent 3,170,272 CONTOUR ABRADHNG MACIHNE AND METHOD Richard C. Burnham, 79'Allen St., Greenfield, Mass. Filed June 3, .163, Se1'. N0. 284,978 1 9 Claims.- (Cl. 51-141) Basically, the present invention comprises the concept of advancing an endless abrading belt and employing suction means to conform a portion ofthe belt to a nonplanar configuration as it thus advanced. 1

To enable aportion of a moving abrading belt to be drawn into conformity with a non-planar contour, the belt must bein aslack or relaxed condition; The degree or extent of slackness naturally depends upon-the extent of deviation, of the contour from the plane of travel of the belt. Since belt tension is a prerequisite to operation of conventional belt sanders, in accordance with this invention, means isrequired for driving a belt without tension. .The abrading belt may beconsidered in slack or relaxed condition when its overall length is greater than the path of travel defined by the. guide means provided forthe belt. The above and other related objects and features of source.

the invention will be apparent from a reading of the following description of the disclosure found in the accornpanying drawings-and the novelty thereof pointed out in the appended claims. a

In the drawings: FIG. 1 is a perspective view of one embodiment of the invention;

FIGS; 2 and .3 are perspectiveviews of means for forming different .types of non-planar contours for the abrading belt; Y

, FIG. 4 is a perspective view of a modified version of the invention; and i 1 1 FIG. 5 isa perspective view of'a'substitute device emcontours.

Referring now to BIG. 1, the illustrated,embodiment {of the present invention may be conveniently mounted on a bench or table tgand comprises an L-shaped frame 1'9 which is secured thereto by screws 12; A motor 14 is mounted on the frame 10 and has a cup-shaped pulley 16 secured to its'shaft. An abrasive belt 18 is trained aroundthe pulley 16 and also around a belt guide 2% spaced from the pulley. The pulleylfi andguide 20 have flanges 22 and 24 respectively to prevent lateral displacement of the belt 18. N I

As shown, the belt guide 20 comprises a member having a semi-cylindrical surface 2.6 disposed between the flanges 24; This guide isrnounted on a bracket 28 which is adjustableonan'arm 30 projecting fromthe frame it for moving the guide toward and-away from the drive pulley 16. A wing nut 32 may be tightened on a screw 34 to lockthe guide 20 in a position properly spaced from the pulley 16. The cylindrical surface of the guide is preferably a material having a low coefficient of friction such as certain plastics, for example Teflon.

A vacuum chamber which may be in the form of a box 36 is disposed within the cup-shaped pulley 15 which further comprises a perforate cylinder. 3%. Vacuum is provided within the chamber by a vacuum :source'connected to the boxfio 'by conduits 40 and 42. The box,

ice

36 provides a vacuum: chamber internally of the perforated cylinder opening toward'the surface portion of the shell 38 around which the belt 18 is trained. The outer edges of the box are sufficiently contiguous with the inner surface of the shell 38 so that a vacuum is drawn principally through \that perforation of the shell 38 around which the belt 18 is trained and against which it is thus drawn and held in contact. The combined action of the vacuum drawing the belt against the cylinder 38 and the rotation of the cylinder serves to drive the belt in a non-tensioned or slack condition. The guide 20 is positioned relative to the drive pulley so that thebelt 18 is slack about guide 20 and the pulley 16.

That is, the length o f the belt is greater than the path of advanced. The vacuum chamber may be, and asshown V is, in the form of a box removably secured, by screws 47, to a' plate 48, which in turn is attached to an arm projecting fromthe frame it). The conduit or pipe 49 is also connected to the plate 48 and communicatestherethrough with the'interior of the chamber 44 to thus provide a vacuum within that chamber byway of the pipe 42 which is connected to the above-mentioned vacuum The contoured surface 46 is perforate so that the belt 18 will be drawn into intimate contact'therewith as it is advanced thereover to thus provide an abrading surface which accurately reproduces the configuration defined by the surface 46. I The sides of the chamber 44 may project outwardly beyond the surface 46,- as indi- 1 dated at 52, to provide further lateral guiding means for the, belt 18.

- The belt 13, as mentioned above, is slack or longe .sanding angles, curves and irregular surfaces.

useful in finishing furniture moldings.

be useful in 'abradi'ng and finishing ployed in connection with FIG.. 4 for forming other -As this point it will be noted that the term abrading is used in its broadest sense to include removal 'of material by rubbing or wearing away. Thus, the outer surface of the belt 18 may take many forms which would be suitable for removing material from wood,. plastic, metal or objects formed of other materials. For example, sand paper oralurninum oxide or tungsten carbide particles could be adhered to the surfac'eof the belt 18. The sizev or grit of these particles would determine the rate of removal and the smoothness of the abraded surface.

Coarse grits are used for rough work and'fine grits for a smooth finish. The abrading surface could even be of felt or equivalent material for a polishing operation.

. Various alternate embodiments of the suction chamber 44 are illustrated in FIGS. 2 and 3, which also illustrate in somewhat greater detailtheconstruction of thefsuction chamber, particularly the openings 54 and 55 which provide communication through the plate 48 with the vacuum source. A gasket g is provided to provide a seal between the chamber and the plate 48, v

FIG. 2 illustrates a vacuum chamber 44' having a a contoured surface 46' which hasa shape particularly which ,is mentioned above as being disposed between the plate 48 and the vacuum chamber; will also be seen in FIG. 2. V "'i V 1 FIG. 3 illustrates a vacuum chamber 44" having a contoured surface 46" which provides'a surface to which i the abrading belt is conformed and which would also i irregularly s'haped articles such asfmoldings.

The gasket g Referring now to FIG. 4, a modified form of the invention will be described. This embodiment is also mounted on a table 2 and comprises an L-shaped frame 100 secured thereto by screws 102. A motor 104 is mounted on the frame and has a cup-shaped pulley 106 secured to its shaft. An abrasive belt 108 is trained around the pulley 106 and also around belt guides 110, 112 and 114. The pulley 106 has flanges 116 which prevent lateral displacement of the'belt 108.

The guides 110, 112 and 114 are mounted on an extension of suction chamber 118, removably secured to a plate 120 by screws 122. As shown, the guide 110 is provided with flanges 127 to prevent lateral displacement of the belt. The plate 120 in turn is supported on the frame 100 by an arm 124 secured thereto. A vaccum chamber 126 is disposed within the cup-shaped pulley 106 which further comprises a perforate cylinder 128. The vacuum chamber, as in the previous embodiment, is preferably semi-cylindrical and provides a chamber which opens on the portion of the cylinder 128 around which the belt 103 is trained. The chamber 126 is connected by conduits 130 and 132 to an appropriate vacuum source. The pulley and vacuum chamber are in all respects similar in operation and construction to the unit shown in FIG. 1. It will be appreciated that the same machine is preferably used for both internal and external sanding operations. Modification from one to the other type of operation may be accomplished by simply changing the contour suction chamber and belt guide element.

The vacuum conduit 130 extends to the plate 120 to connect the suction chamber 118 to the same vacuum source. The suction chamber 118 has an extension 133 which projects beyond the frame 100 and with its upper surface provides a contour plate 134 which is convexly curved transversely of the belt 103. This arrangement provides a projecting convex abrading surface of the moving belt type which is readily available for abrading concavely curved surfaces and particularly such surfaces as the interior diameters of tubular or ring-like elements. Flanges 129 project from the suction box 113 and together with the flanges 127 and 116 of the pulley 106 prevent lateral displacement of the belt 108.

FIG. shows a substitute suction box 118' which ranged for the abrading of surfaces which are joined at a relatively sharp angle. Thus, it is preferable that the contour plate 134 have perforate surfaces which arejoined along a line transversely of the belt 108 at an angle a which may be 90 or any other suitable angle for the job requirements.

In using the suction box 118 the belt 108 is advantageously slack, as in the embodiment described in connection with FIG. 1 so that there is a minimum of tension on the belt as it is advanced over the corner at which the two perforate surfaces meet.

While in accordance with this invention the belt drive advances the belt in a slack condition, it will be realized that for certain contours, such as in the embodiment shown in FIG. '4, that the abrasive belt could ,be som what tensioned and yet drawn into conformity with the configuration of the contour plate 134. The relative tension or slackness depends on tent of the curvature.

the direction and ex-' The surfaces of the contour suction chamber in contact with the abrading belt may be made of suitable low friction material to minimize belt wear.

Having thus described the invention, what is claimed is:

1. A method of contour abrading which comprises the steps of continuously advancing an endless abrading belt in slack condition and drawing a portion of the moving belt by suction into a non-planar concave configuration for abrading contoured surfaces.

2. A method of contour abrading which comprises the steps of advancing an endless abrading belt in slack condition by employing a rotating pulley and gripping the belt against the pulley through the use of suction means, and drawing a portion of the slack belt by suction into a concave configuration for abrading contoured surfaces.

3. Contour abrading machine comprising means for 5. Method of contour abrading which comprises the steps of continuously advancing an endless abrading belt in a substantially slack condition about a given path by rotating a perforated pulley and gripping the belt thereagainst by the use of suction, and drawing a portion of the slack belt by suction into a concave configuration for abrading contoured surfaces.

. 6. A contour abrading device as in claim 4 wherein "the advancing means include a rotating pulley around which the belt is trained and vacuum means for gripping portions of the belt trained around the pulley thereagainst to thus advance the belt.

7. A contour abrading device as in claim 4 wherein conforming means comprises a perforate plate having two angilarly disposed surfaces joined at a line transversely of said belt, the belt being advanced over the side of the plate having the named surfaces and the other side of said plate defining a suction chamber and means connecting the suction chamber to a vacuum source.

8. A contour abrading device as in claim 7 wherein the pulley comprises a'perforate cylinder, means disposed within said cylinder forming a suction chamber, said chamber having an opening communicating with that portion of the pulley cylinder around which the belt is trainedand means connecting said'chamber to a vacuum source. 9. A contour abrading device as in claim 8 wherein the angle between the two named surfaces is approximat-ely degrees and the perforate plate also defines one limit of the path of travel of said belt.

References Cited by the Examiner UNITED STATES PATENTS 1,949,237 2/34 Br-adner 226 X 7 1,999,275 4/35 Bertrand.

2,296,990 9/42 Fowler 51141 2,984,398 5/61 Chalmers 226-95 3,110,431 11/ 63 Potter et al. 226-95 I LESTER M. SWINGLE, Primary Examiner. 

3. CONTOUR ABRADING MACHINE COMPRISING MEANS FOR CONTINUOUSLY ADVANCING AN ENDLESS ABRADING BELT IN A SLACK CONDITION ABOUT A PATH, A CONTOURED SURFACE DISPOSED WITHIN SAID PATH AND SUCTION MEANS FOR DRAWING A PORTION OF THE ABRADING BELT INTO SURFAC-TO-SURFACE CONFORMITY WITH SAID CONTOURED SURFACE. 